JP2023048164A - Illumination optical part and video projection device using the same - Google Patents

Abstract

To provide an illumination optical part which achieves both miniaturization of an optical system and high image quality, and also to provide a video projection device having a video display part which displays a video using the same.SOLUTION: Disclosed is an illumination optical part for illuminating a video display part for displaying a video, which includes: a light source for emitting light; a lens part for converting the divergent light from the light source into substantially collimated light; an optical path of the illumination light in which the light emitted from the lens part enters and goes to the video display part; and an optical branching part for branching the light from the video display part to the optical path on the projection part side. The optical branching part has two or more emission reflecting surfaces for emitting the illumination light.SELECTED DRAWING: Figure 6

Description

The present invention relates to an image projection apparatus having an illumination optical unit for displaying images and an image display unit for displaying images using the same.

Video projection devices such as projectors and head-mounted displays (hereinafter also abbreviated as HMDs) are required to have not only display performance such as video visibility, but also a structure that is compact and excellent in portability and wearability.

There is Patent Document 1 as a prior art document in this technical field. Patent Document 1 discloses a light source that emits light, and one light having a specific polarization component among the light emitted from the light source is transmitted, and the other light having a polarization component orthogonal to the specific polarization component is used for projection. Separating means for reflecting toward an optical system; image forming means, which is a liquid crystal element utilizing the one light, modulates and reflects the incident light and emits it as projection light; and the separating means. a reflecting means for rotating the polarization direction of the projection light incident on and reflected by the optical system for projection and emitting the projection light toward the projection optical system; analyzing the projection light emitted by the reflecting means; A projector is disclosed that includes a reflective polarizing plate that reflects other light reflected back to the light source.

JP 2009-265549 A

In Patent Document 1, the optical system of the image projection device is composed of an illumination unit that transmits light emitted by the light source unit to the image display unit, and an image generation unit that has a projection unit that projects the image light generated by the image display unit. . The lighting section consists of a light source that emits light, a color mixing section that mixes the light from each light source, a brightness equalization section that illuminates the small display with uniform brightness, and a light branching section that switches the optical path to the projection section. Various functions for achieving high-quality image display, such as means for uniformity, are implemented by independent optical components. Therefore, there is a problem that the size of the apparatus is increased.

That is, in Patent Document 1, these problems are not taken into consideration in achieving both high image quality of the displayed image of the image projection device and miniaturization of the optical system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image projection apparatus having an illumination optical unit that achieves both miniaturization of an optical system and high image quality, and an image display unit that uses the illumination optical unit to display an image.

An example of the present invention is an illumination optical unit that illuminates an image display unit that displays an image, comprising a light source that emits light, a lens unit that converts divergent light from the light source into substantially collimated light, An optical path of illumination light directed to the image display unit where the light emitted from the lens unit is incident and a light branching unit for branching the light from the image display unit to the optical path on the projection unit side, the light branching unit diverting the illumination light. It is configured to have two or more output reflecting surfaces for output.

According to the present invention, it is possible to provide an image projection apparatus having an illumination optical unit that achieves both miniaturization of an optical system and high image quality, and an image display unit that uses the illumination optical unit to display an image.

2 is a functional block configuration diagram of a video projection device according to Embodiment 1. FIG. 2 is a block configuration diagram showing an example of a hardware configuration of a video projection device as an HMD in Embodiment 1; FIG. 3 is a block configuration diagram of an image generation unit mounted on the HMD in Example 1. FIG. 3 is a block configuration diagram of an image generation unit mounted on the projector in Embodiment 1. FIG. 4A and 4B are diagrams showing usage patterns of the HMD in Example 1. FIG. FIG. 4B is an enlarged view of the video generator in FIG. 4A; FIG. 11 is a configuration diagram of a conventional video generation unit; 4 is a configuration diagram of a video generation unit in Example 1. FIG. FIG. 10 is a configuration diagram of a modified example of the video generation unit in Embodiment 1; FIG. 10 is a configuration diagram of a modified example of the video generation unit in Embodiment 1; FIG. 10 is a configuration diagram of a modified example of the video generation unit in Embodiment 1; FIG. 10 is a configuration diagram of a modified example of the video generation unit in Embodiment 1; FIG. 10 is a configuration diagram of a video generation unit equipped with a transmissive liquid crystal panel in Example 2; FIG. 11 is a configuration diagram of a video generation unit equipped with a DMD panel in Example 2; FIG. 11 is a diagram showing an example of using an HMD in Example 3; FIG. 11 is a functional block configuration diagram of an HMD in Example 3;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a functional block configuration diagram of a video projection device according to this embodiment. In FIG. 1, the video projection device 1 is an HMD or a projector, and includes a video generation unit 101, a control unit 102, an image signal processing unit 103, a power supply unit 104, a storage unit 105, and a sensing unit 106. , a communication unit 107, an audio processing unit 108, an imaging unit 109, and input/output units 91-93.

The image generation unit 101 enlarges and projects an image generated by a small display unit, which will be described later, and displays the image. For example, if the image projection device 1 is an HMD, the image generation unit 101 enlarges and projects the image generated by the small display unit as a virtual image, and displays augmented reality (AR) or mixed reality in the visual field of the wearer (user). A real (MR: Mixed Reality) image is displayed.

The control unit 102 centrally controls the entire image projection apparatus 1 . The functions of the control unit 102 are realized by an arithmetic device such as a CPU. The image signal processing unit 103 supplies a display image signal to the display unit in the image generation unit 101 . The power supply unit 104 supplies power to each unit of the video projection device 1 .

The storage unit 105 stores information necessary for processing of each unit of the image projection device 1 and information generated by each unit of the image projection device 1 . In addition, when the functions of the control unit 102 are implemented by a CPU, programs and data to be executed by the CPU are stored. The storage unit 105 is configured by a storage device such as a RAM (Random Access Memory), flash memory, HDD (Hard Disk Drive), SSD (Solid State Drive), or the like.

The sensing unit 106 is connected to various sensors via an input/output unit 91, which is a connector, and based on signals detected by the various sensors, the orientation of the video projection device 1, that is, the orientation of the user, the orientation of the user's head, and the orientation of the user's head. Detects the tilt, motion, ambient temperature, etc. of the projector. As various sensors, for example, an inclination sensor, an acceleration sensor, a temperature sensor, a GPS (Global Positioning System) sensor for detecting user position information, and the like are connected.

The communication unit 107 communicates with an external information processing device by short-range wireless communication, long-range wireless communication, or wired communication via an input/output unit 92 that is a connector. Specifically, communication via Bluetooth (registered trademark), Wi-Fi (registered trademark), mobile communication network, universal serial bus (USB, registered trademark), high-definition multimedia interface (HDMI (registered trademark)), etc. I do.

The audio processing unit 108 is connected to an audio input/output device such as a microphone, an earphone, or a speaker via an input/output unit 93 that is a connector, and inputs or outputs an audio signal. The imaging unit 109 is, for example, a compact camera or a compact TOF (Time Of Flight) sensor, and captures the view direction of the user of the video projection device 1 .

FIG. 2 is a block configuration diagram showing an example of the hardware configuration of the image projection device 1 as an HMD. As shown in FIG. 2, the image projection apparatus 1 includes a CPU 201, a system bus 202, a ROM (Read Only Memory) 203, a RAM 204, a storage 210, a communication processor 220, a power supply 230, a video It comprises a processor 240 , an audio processor 250 and a sensor 260 .

A CPU 201 is a microprocessor unit that controls the entire image projection apparatus 1 . A CPU 201 corresponds to the control unit 102 in FIG. A system bus 202 is a data communication path for transmitting and receiving data between the CPU 201 and each operation block in the video projection apparatus 1 .

The ROM 203 is a memory that stores a basic operation program such as an operating system and other operation programs. For example, a rewritable ROM such as an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash ROM can be used. .

A RAM 204 serves as a work area for executing the basic operation program and other operation programs. The ROM 203 and RAM 204 may be integrated with the CPU 201 . Also, the ROM 203 may use a partial storage area in the storage 210 instead of the independent configuration shown in FIG.

The storage 210 stores an operation program and operation setting values of the video projection device 1, personal information 210a of the user who uses the video projection device 1, and the like. Although not particularly exemplified below, an operation program downloaded from a network and various data created by the operation program may be stored. Also, a part of the storage area of the storage 210 may be replaced with a part or all of the functions of the ROM 203 . Devices such as flash ROM, SSD, and HDD may be used for the storage 210, for example. ROM 203 , RAM 204 and storage 210 correspond to storage unit 105 . The operation programs stored in the ROM 203 and storage 210 can be updated and expanded in function by executing download processing from each device on the network.

The communication processor 220 includes a LAN (Local Area Network) communication device 221 , a telephone network communication device 222 , an NFC (Near Field Communication) communication device 223 and a BlueTooth communication device 224 . A communication processor 220 corresponds to the communication unit 107 in FIG. 2 illustrates the case where the communication processor 220 includes the LAN communication device 221, the NFC communication device 223, and the BlueTooth communication device 224. As described in FIG. may be connected as a device external to the video projection apparatus 1 . The LAN communication device 221 is connected to a network via an access point and transmits and receives data to and from devices on the network. The NFC communication device 223 performs wireless communication to transmit and receive data when a corresponding reader/writer comes close to it. The BlueTooth communication device 224 wirelessly communicates with an adjacent information processing device to transmit and receive data. Note that the video projection device 1 may have a telephone network communication device 222 for transmitting/receiving calls and data to/from a base station of a mobile telephone communication network.

The virtual image generation mechanism 225 corresponds to the image generation unit 101 in FIG. A specific configuration of the virtual image generation mechanism 225 will be described later with reference to FIG. 3A.

The power supply device 230 is a power supply device that supplies power to the video projection device 1 according to a predetermined standard. Power supply 230 corresponds to power supply unit 104 in FIG. 2 illustrates the case where the video projection device 1 includes the power supply device 230, these are connected as external devices of the video projection device 1 via any of the input/output units 91 to 93, and the video The projection device 1 may receive power supply from the external device.

The video processor 240 comprises a display 241 , an image signal processor 242 and a camera 243 . The image signal processor 242 corresponds to the image signal processor 103 in FIG. The camera 243 corresponds to the imaging section 109 in FIG. 1, and the display 241 corresponds to a small display section described later. FIG. 2 illustrates a case where the video processor 240 includes a display 241 and a camera 243. As described with reference to FIG. It may be connected as an external device of the projection device 1 .

The display 241 displays image data processed by the image signal processor 242 .

The image signal processor 242 causes the display 241 to display the input image data. The camera 243 uses an electronic device such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor to convert the light input from the lens into an electrical signal, thereby inputting image data of the surroundings and objects. It is a camera unit that functions as an imaging device.

The audio processor 250 comprises a speaker 251 , an audio signal processor 252 and a microphone 253 . Audio processor 250 corresponds to audio processor 108 in FIG. FIG. 2 illustrates the case where the audio processor 250 includes the speaker 251 and the microphone 253. As described with reference to FIG. may be connected.

Speaker 251 outputs the audio signal processed by audio signal processor 252 . Audio signal processor 252 outputs the input audio data to speaker 251 . The microphone 253 converts voice into voice data and outputs it to the voice signal processor 252 .

The sensor 260 is a sensor group for detecting the state of the image projection device 1, and includes a GPS receiver 261, a gyro sensor 262, a geomagnetic sensor 263, an acceleration sensor 264, an illuminance sensor 265, and a proximity sensor 266. is configured with A sensor 260 corresponds to the sensing unit 106 . FIG. 2 illustrates a case where the sensor 260 includes a GPS receiver 261, a gyro sensor 262, a geomagnetic sensor 263, an acceleration sensor 264, an illuminance sensor 265, and a proximity sensor 266. 1, these may be connected as external devices of the video projection apparatus 1 via the input/output unit 91 . Since each of these sensors is a conventionally known general sensor group, the description thereof is omitted here. Also, the configuration of the image projection device 1 shown in FIG. 2 is merely an example, and it is not necessary to include all of them.

FIG. 3A is a block configuration diagram of the video generation unit 101 mounted on the HMD. The image generation unit 101 includes an illumination optical unit 120 , an image display unit 121 , a projection unit 122 and a light guide unit 123 .

An illumination optical unit 120 irradiates light from a light source such as an LED or a laser onto an image display unit 121, which is a small display unit. The image display unit 121 is an element for displaying images, and uses a liquid crystal display, a digital micromirror device, an organic EL display, a micro LED display, a MEMS (Micro Electro Mechanical Systems), a fiber scanning device, or the like. The projection unit 122 is a device that magnifies the image light of the image display unit 121 and projects it as a virtual image. The light guide section 123 is a light guide plate that replicates the image light for enlarging the eyebox and transmits the image light from the projection section 122 to the user's pupil 20 . A user can visually recognize an image by forming an image of the image light on the retina in the pupil 20 .

FIG. 3B is a block configuration diagram of the video generation unit 101 mounted on the projector. 3B differs from FIG. 3A in that it does not have a light guide section 123. The image generation section 101 is composed of an illumination optical section 120, an image display section 121, and a projection section 122. The projection section 122 is , magnifies the image light of the image display unit 121 and projects it onto the screen 124 located outside.

4A and 4B are diagrams showing usage patterns of the HMD 10 in this embodiment. FIG. 4A shows a state of looking down from the overhead direction of the user 2, the X axis is the horizontal direction, the Y axis is the vertical direction, and the Z axis is the visual axis direction, which is the line of sight of the user 2. FIG. The directions of the X-, Y-, and Z-axes are similarly defined in the subsequent drawings. FIG. 4B is an enlarged view of the image generator 101 in FIG. 4A.

As shown in FIG. 4A, the HMD 10 is worn on the head of the user 2, and the images generated by the illumination optical unit 120, the image display unit 121, and the projection unit 122 are propagated to the user's eyes 20 via the light guide unit 123. Let At that time, the user 2 can visually recognize an image (virtual image) in a state (see-through type) in which the outside world can be visually recognized in a partial image display area 111 within the field of view. Note that FIG. 4A shows a configuration in which images are displayed on both eyes, but a single-eye configuration may also be used. Also, the HMD 10 can capture an image of the visual field range of the user 2 in the imaging unit 109 of FIG.

The eyebox formed by the image generation unit 101 is desirably enlarged in the two-dimensional direction from the viewpoint of image visibility. If functions are implemented in the illumination optical unit 120, the image display unit 121, and the projection unit 122 in order to improve the image quality and brightness, the number of optical parts increases and the size of the apparatus increases.

As shown in FIG. 4A, since the HMD is a device that is worn on the body, it is possible to display augmented reality with the same usability as conventional eyeglasses in terms of weight, wearability, and appearance design. It is an important element and an important point in increasing product value.

Further, as shown in FIG. 4B, the light guide portion 123 is a light guide plate having two substantially parallel flat plate-like main surfaces 191 and 192, and has at least two or more light guide plates inside to enlarge the eyebox. has an output reflecting surface 126 which is a partially reflecting surface of the . The light guide section 123 has a function of propagating the image light output from the projection section 122 by total reflection, and replicating the image light of the projection section 122 by the output reflection surface 126 having a reflection film that reflects a part of the image light. have In addition, it is desirable that the output reflecting surfaces 126 are substantially parallel to each other so that the reflected image light is not angularly misaligned.

The illumination optical unit 120, the image display unit 121, and the projection unit 122 can be arranged outside the field of view due to the image light transmission function of the light guide unit 123, and by reducing the reflectance of the output reflection surface 126, the surrounding Both see-through properties and visual recognition of images can be achieved.

For example, if a self-luminous panel such as an organic EL or a micro LED is used for the image display unit 121, the illumination optical unit 120 becomes unnecessary and the size reduction of the image generation unit 101 can be expected. However, there is a limit to the significant improvement in luminous efficiency of a self-luminous panel equipped with minute luminous pixels, and from the viewpoint of ensuring see-through properties of the light guide section 123, it is desirable to set the reflectance of the output reflection surface 126 high. Since it is not possible, a trade-off relationship arises in the utilization efficiency of the image light. Therefore, the image generation unit equipped with the light guide unit 123 is required to output a high-brightness image. There is a problem of shortage.

Even in the case of a projector, if a self-luminous panel is used for the image display unit 121, the illumination optical unit 120 becomes unnecessary, and the size reduction of the image generation unit 101 can be expected. A projector that projects an enlarged image onto a screen also requires a high optical output for the image display section. However, there is a limit to the significant improvement in luminous efficiency of a self-luminous panel equipped with minute light-emitting pixels, and if the image display section 121 is a self-luminous panel, it is not possible to obtain sufficient image brightness with current device performance. There is a problem.

As described above, projectors and HMDs have a problem in achieving both compactness and high brightness of the illumination system. These solutions are described below.

FIG. 5 is a configuration diagram of a conventional video generation unit. The image generation unit is composed of an illumination optical unit 120 , an image display unit 121 and a projection unit 122 . The illumination optical unit 120 irradiates the image display unit 121 with light from a light source such as an LED or laser. The image display unit 121 is a microdisplay for displaying images, and uses a liquid crystal display, a digital micromirror device, or the like. The projection unit 122 magnifies the image light of the image display unit 121 and projects it as a virtual image.

The illumination optical unit 120 includes a green (G) light source 140 and red (R) and blue (B) light sources 141 as light source units. Light from each light source is substantially collimated by condenser lenses 142 and 143 . Approximately collimated light from each color light source is synthesized by the color synthesizing unit 144 .

FIG. 5 shows an example in which a wedge-shaped dichroic mirror is used for the color synthesizing unit 144 . The dichroic mirror synthesizes substantially collimated light of R light, B light, and G light and emits the combined light. At this time, the optical axes of the respective colors do not necessarily have to match perfectly, and the optical axes may be slightly shifted so that the intensity distributions on a predetermined plane substantially match.

The color-combined light is incident on the microlens array 130 that serves as a virtual secondary light source. The microlens array 130 is illuminated with a substantially collimated light flux emitted from the color synthesizing section 144 . By using the microlens array 130 as luminance uniforming means, light can be collected only in a predetermined range of the microdisplay of the image display section 121 . Moreover, there is an advantage that the luminance distribution of the illumination light on the image display section 121 can be made uniform and the image quality can be improved.

A condensed lens 131 as a condensed optical member forms a cell image of the microlens array 130 on the image display section 121 .

Light branching for guiding the outward optical path toward the image display unit 121 and the light from the image display unit 121 to the projection optical path on the projection unit side when LCOS (Liquid Crystal On Silicon, registered trademark) or the like is used for the image display unit 121. A section 132 is provided. The light branching section 132 separates the optical path to the illumination optical section 120 and the projection section 122 . The projection unit 122 projects the image on the image display unit 121 at infinity or as a virtual image. The image light from the projection unit 122 is incident on the light guide unit 123, and the user can visually recognize the image while ensuring the see-through property.

When viewing an image with the optical system, a conjugate image of the light sources 140 and 141 duplicated by the microlens array 130 is formed on the exit surface of the microlens array 130 . Further, the exit surface of the microlens array 130 and the exit pupil of the projection unit 122 are in a substantially conjugate positional relationship. Therefore, at the exit pupil position 122p of the projection unit 122, a conjugate image of the light sources 140 and 141 formed on the exit surface of the microlens array 130 and a conjugate image of the microlens cell exit surface of the microlens array 130 itself are formed. be done. Therefore, when the user views the image through the light guide plate, it appears that the conjugate image of the microlens cells and the conjugate image of the light source are superimposed in front of the image, and the visibility of the image deteriorates.

Since the light guide plate has a function of duplicating the exit pupil of the projection unit 122 in order to enlarge the eyebox, if the number of duplications is large, the conjugate images may repeatedly overlap and become inconspicuous. On the other hand, when a beam splitter mirror array type light guide plate is used, the number of times of duplication is theoretically reduced compared to other methods, and the visibility of the image is greatly reduced due to the conjugate image.

Therefore, as a configuration for suppressing the visibility of the conjugate image of the microlens cell and the light source, a luminance equalizing means for diffusing the light from the microlens array 130 and equalizing the luminance is provided in the vicinity of the condensed lens 131 of the illumination optical unit 120. A diffusion plate 133 is provided as a By providing the diffuser plate 133, the conjugate image of the microlens cell and the light source can be blurred and made inconspicuous. At this time, by arranging diffusion plate 133 in front of image display unit 121 , resolution of an enlarged image (virtual image) of image display unit 121 by projection unit 122 can be prevented from being affected. As described above, the HMD 10 using the light guide plate has a problem of generating a conjugate image, which can be suppressed by providing the diffusion plate 133 .

As described above, among the conventional image generating units, the illumination optical unit 120 has a function of collimating the light from the light source with a lens, a function of mixing collimated light from each light source with a dichroic mirror, a microlens array, and a condenser lens. Since various functions such as a uniform luminance distribution function and a function for branching an optical path by polarization are implemented by independent optical components, there is a problem that the size increases.

Therefore, if an optical component having a plurality of functions can be provided for the illumination optical unit 120, miniaturization can be achieved.

FIG. 6 shows the configuration of the video generation unit 101 in this embodiment. In FIG. 5, the light source 140 emits green light, and the light source 141 is a light source that emits red and blue light, both of which are mounted in the same package. light sources are integrated in the same package. That is, the light source 150 is a multi-chip light source in which a red chip, a green chip, and a blue chip that emit light in red, green, and blue wavelength bands are mounted in one housing.

Furthermore, in FIG. 6, a compact light integrator 151 that enhances color mixture and uniformity is mounted in order to downsize the illumination optical section. The light integrator 151 has a shape similar to a quadrangular prism or cylinder, and its interior is filled with a medium A having a predetermined high transparency. The light integrator 151 also has an incident surface 152, an exit surface 153, and side surfaces. An incident surface 152 and an exit surface 153 are surfaces from which light enters and exits, respectively. It is known from Snell's law that a light ray larger than the critical angle cannot travel from a medium with a high refractive index to a medium with a low refractive index, and undergoes total internal reflection (hereinafter referred to as TIR). Therefore, the side surface of the light integrator 151 is a surface having a function of confining the light incident from the incident surface 152 by TIR.

Since the light emitted from the light integrator 151 becomes divergent light, it is converted into approximately collimated light by the condensing lenses 142 and 143 . By using the light integrator 151, light can be confined and diffused, and the light from the multi-chip light source can be efficiently mixed and homogenized in a limited space. 101 illumination optics 120 can be provided.

The interior of the light integrator 151 may be randomly filled with scattering particles 154 filled with a highly transparent medium B having a refractive index different from that of the medium A. According to Snell's law, a ray of light exits at a different angle from the angle of incidence when passing through media with different refractive indices. The scattering particles 154 use this principle and have the function of changing the angle of the propagating light beam to scatter it. The scattering particles may be spherical or have other shapes. By including scattering particles, it is possible to efficiently mix and homogenize light even in a shorter length light integrator.

The light emitted from the condensing lenses 142 and 143 enters the light guide plate type light branching portion 132W. The light branching portion 132W has a pair of substantially parallel flat plate-like main surfaces 155 and 156 that confine the illumination light by total internal reflection, and two or more exit reflection surfaces that emit the illumination light to the outside of the light branching portion. It has an output reflection surface group 157 inside. Further, there may be an incident reflecting surface 158 that reflects the illumination light to the inside of the light branching portion 132W.

FIG. 6 illustrates a case where the internal reflection is total reflection by two parallel planes. However, it does not necessarily have to be total reflection. A light guide plate having parallel planes that produce diffuse reflection may be used.

The light branching unit 132W needs to transmit the image to the illumination or projection side without omission of the effective area of the image display unit 121 . Therefore, as shown in FIG. 5, the conventional optical splitter 132 needs to be provided with a reflective surface 132R having a size larger than the effective area of the image display unit 121, resulting in an increase in size. In the light branching unit 132W of this embodiment, if the distance between the adjacent output-reflecting surfaces of the output-reflecting surface group 157 is L1, and the length of the side in the arrangement direction of the output-reflecting surfaces in the effective area of the image display unit 121 is LA, then: LA>L1 is established, and a plurality of exit/reflection surfaces having intervals smaller than the effective area of the image display section 121 are arranged. As a result, the thickness of each output/reflection surface can be reduced, so that the thickness of the light branching portion 132W is reduced as a whole.

Also, the screen aspect ratio of the displayed image is generally 16:9 or 4:3 rather than 1:1, which has the same vertical and horizontal ratio. Therefore, the effective area of the image display unit 121 also has an aspect ratio, and the short side direction of the effective area is substantially parallel to the direction in which the output reflecting surfaces of the output reflecting surface group 157 of the light branching unit 132W are arranged. It is possible to reduce the number of necessary outgoing reflection surfaces to be arranged and to reduce the cost.

For example, when a liquid crystal microdisplay is used for the image display unit 121, ON/OFF of the pixel is switched by rotating the polarization direction of the illumination light at each pixel of the microdisplay. Therefore, it is desirable that the reflecting film formed on the output reflecting surface of the output reflecting surface group 157 of the light branching portion 132W be a polarizing reflecting film.

For example, consider the case where S-polarized illumination light is reflected by the exit/reflection surface group 157 to illuminate the image display section 121 . When the image display unit 121 is a microdisplay using liquid crystal, the polarization direction is rotated, for example, by 90° at pixels that are turned ON, and P-polarized light is incident on the exit reflection surface group 157 from the image display unit 121 . Since the output reflecting surface group 157 has a polarizing property, the P-polarized light is transmitted and guided to the projection unit 122, and the ON pixels are projected through the projection unit 122, whereby the ON pixels are visually recognized by the user.

Here, in the case of a general polarization beam splitter in which the reflection characteristics of the output reflection surface group 157 reflect approximately 100% of S-polarized light and transmit approximately 100% of P-polarized light, the incident portion of the light branching portion 132W has All of the light is reflected by the exit/reflection surfaces of the nearest exit/reflection surface group 157 , making it difficult to illuminate the entire effective area of the image display section 121 . Therefore, in this case, the output reflecting surface group 157 is a group of partially reflecting surfaces that partially reflects S-polarized light and partially transmits S-polarized light and P-polarized light, and the partially reflecting surfaces are arranged in an array. .

Furthermore, since the output reflecting surface group 157 of the light branching part 132W in this embodiment is composed of two or more output reflecting surfaces, the light traveling through the element is gradually reflected each time it passes through the output reflecting surface, and the amount of light is reduced. While proceeding inside. Therefore, if the reflectances of the exit reflection surface group 157 are all the same, the amount of light that illuminates the image display section 121 will be uneven within the region. Therefore, as an example, the reflectance of each output reflection surface of the output reflection surface group 157 is configured to increase as the distance from the incident portion to the light branching portion 132W increases, thereby improving the uniformity of the illumination light. Further, when the output reflecting surface group 157 is a reflecting film having a polarizing property, the reflectance of each output reflecting surface is configured such that the S-polarized light reflectance increases as the distance from the incident portion to the light branching unit 132W increases. Light uniformity can be improved. Therefore, from the viewpoint of light utilization efficiency, it is desirable to set the S-polarized light reflectance of the output reflection surface far from the incident portion of the light branching portion 132W to approximately 100% from the viewpoint of light utilization efficiency.

If the reflectance of the partial reflection surface of the output reflection surface group 157 is set low, the luminance uniformity of the illumination light within the effective area of the image display section 121 is improved, but the light utilization efficiency is lowered. On the other hand, if the reflectance is increased, the light utilization efficiency is improved, but the brightness uniformity of the illumination light is lowered as described above. Therefore, from the viewpoint of light utilization efficiency and luminance uniformity, it is desirable that the S-polarization reflectance of the partial reflection surface of the output reflection surface group 157 is between 5% and 60%.

On the other hand, if the reflectance of the output reflection surface group 157 is kept low, even if the reflectances are all the same, that is, even if the same reflection film is used for each of the partial reflection surfaces, it will not cause a large luminance unevenness. Rather, since each partially reflective surface can be processed in the same film forming process, the manufacturing cost can be reduced. From the viewpoint of ensuring both luminance uniformity and see-through properties, it is desirable that the reflectance of the exit reflecting surface group 157 is 10% or less.

In addition, when the image display unit 121 and the light branching unit 132W are arranged at positions very close to the projection unit 122, the image projected from the projection unit 122 is reflected by the emission reflection surface group 157 of the light branching unit 132W. The reflective surface boundary may also be visually recognized. Therefore, in consideration of the depth of focus of the projection lens, a predetermined distance is required between the image display section 121 and the light branching section 132W. Considering the depth of focus of the projection unit used in general small projectors and HMDs, it is desirable that there is a distance of 1 mm or more between the main surface 155 of the light branching unit 132W on the display unit side and the image display unit 121 according to the author's study. .

In addition, it is desirable that the output reflecting surface group 157 of the light branching section 132W be parallel to each other from the viewpoint of manufacturability. That is, it is desirable that the partial reflection surfaces (output reflection surfaces) of the output reflection surface group 157 are parallel to each other. By laminating and integrating a plurality of parallel flat plates each having a partially reflecting surface, and then cutting them into a predetermined shape, it is possible to collectively process from the incident surface to the output reflecting surface, and also to cut out a plurality of light branching portions 132W. This is because it becomes possible. Therefore, by making the partial reflection surfaces (output reflection surfaces) of the output reflection surface group 157 of the light branching portion 132W parallel to each other, there is an advantage that the manufacturing process can be simplified and the manufacturing cost can be reduced.

If there is an overlap between the adjacent exit/reflection surfaces of the exit/reflection surface group 157 of the light branching portion 132W, the luminance of the overlapping portion becomes high and the luminance uniformity of the illumination light is reduced. On the other hand, if there is a gap between the adjacent output/reflecting surfaces, the luminance at the gap is reduced, resulting in reduced luminance uniformity. Therefore, when the thickness of the light branching portion 132W is t, and the angle of the output/reflection surface is θ, the relationship between the output/reflection surface interval L1 and the distance L1 is t/tan θ≈L1, thereby improving luminance uniformity.

As described above, the conventional optical branching portion 132 without a total reflection confinement function has a problem that the outer shape becomes large in order to prevent the generation of stray light on the side surface thereof. Since the image light is confined by , there is an advantage that the illumination light and the projection light can be branched while reducing the size of the device.

Next, a method for improving contrast in this embodiment will be described. As described above, for example, the case where S-polarized illumination light is reflected by the output reflection surface group 157 to illuminate the image display section 121 is considered. When the image display unit 121 is a microdisplay using liquid crystal, the polarization direction rotates in pixels that are turned ON, and P-polarized light is incident from the image display unit 121 on the exit reflection surface group 157 . Since the output reflecting surface group 157 has a polarizing property, the P-polarized light is transmitted and guided to the projection unit 122, and the ON pixels are projected through the projection unit 122, whereby the ON pixels are visually recognized by the user. On the other hand, in the case of OFF, S-polarized light returns from the image display unit 121 to the exit reflection surface group 157 without changing the polarization direction. At this time, the OFF light is S-polarized light, and the output reflecting surface group 157 has a reflectance characteristic of reflecting part of the S-polarized light. Therefore, there is a problem that the S-polarized light is also transmitted through the output reflecting surface group 157 and is visually recognized by the user via the projection unit 122 . Pixels that should be displayed as black due to lack of light have the amount of light, resulting in projection of a so-called floating black image with low contrast.

Therefore, a polarizing filter 160 that absorbs or reflects light polarized in a predetermined direction may be arranged between the light branching section 132W and the projection section 122 in order to improve the contrast. The contrast of the projected image can be greatly improved by absorbing only S-polarized light corresponding to the OFF light described above, for example, with a polarizing filter. Although not shown, the polarizing filter 160 may be arranged anywhere on the projection section 122 side from the light branching section 132W, and may be arranged on the output side of the projection section 122 or within the projection section 122 .

In the configuration shown in FIG. 6, the light emitted from the light integrator 151 becomes divergent light and is converted into approximately collimated light by the condensing lenses 142 and 143 . Due to the relationship between the condensing lenses 142 and 143 and the projection section 122, a conjugate image of the exit surface 153 of the light integrator 151 appears at the exit pupil position 122p of the projection section 122, which has a substantially conjugate positional relationship. Therefore, when the user views the image through the light guide plate, the conjugate image of the exit surface 153 of the light integrator 151 appears to be superimposed in front of the image, resulting in poor visibility of the image.

Further, as mentioned above, the light guide plate has the function of duplicating the exit pupil of the projection section 122 to enlarge the eyebox. Therefore, especially when a beam splitter mirror array type light guide plate is used, the conjugate image is duplicated on the light guide plate and the visibility of the image is greatly reduced.

Therefore, a diffuser plate 161 is provided between the condensing lenses 142 and 143 and the light branching portion 132W as luminance uniforming means. Light is diffused by the diffuser plate 161, and the outline of the conjugate image on the exit surface 153 of the light integrator 151 is blurred to reduce visibility and improve image quality. On the other hand, since the diffusion plate 161 does not affect the projection side, the resolution of the output image is not deteriorated.

In many cases, an inexpensive LED element is used for the light source, and in that case, the output light is non-polarized light. In order to improve the contrast, it is important to separate the polarized light as described above, and the efficiency of the entire optical system can be improved by making only the S-polarized illumination light incident on the exit reflecting surface group 157 . For example, by mounting the polarizing filter 162 at the same position as the diffusion plate 161 described above, the polarization direction of the illumination light incident on the light branching portion 132W can be aligned in a predetermined direction, thereby improving the contrast of the displayed image.

The diffusing plate 161 has the effect of disturbing the polarization direction of the illumination light by scattering, and the polarizing filter 162 on the illumination side is placed after the illuminating light passes through the diffusing plate 161 to improve the uniformity of the polarization and improve the contrast. be done. Therefore, it is desirable to dispose the polarizing filter 162 between the light splitter 132W and the diffusion plate 161. FIG.

7A to 7D are modifications of the video generation unit 101 having the light branching unit 132W in this embodiment. 7A differs from FIG. 6 in the configuration of the optical integrator 151. FIG. In FIG. 7A, light integrator 151 is integrated with a transparent layer, which is a transparent optical medium containing no scattering particles, and a scattering layer containing scattering particles 154 . Incident light from the light source 150 is scattered in the light integrator 151, but the scattering is not only forward but also backward. A large amount of returning light is generated, and the light utilization efficiency is lowered. Therefore, a transparent layer, which is a transparent optical medium that does not contain scattering particles, is provided on the incident surface 152 side so that colors are mixed only by total internal reflection, and scattering particles are provided on the exit surface side to greatly diffuse (mix colors) immediately before exiting. By doing so, it is possible to provide the optical integrator 151 that achieves both light utilization efficiency and miniaturization.

FIG. 7B shows a modification in which the exit surface 153 of the light integrator 151 in FIG. 6 has a convex shape. In the configuration shown in FIG. 6, the light emitted from the light integrator 151 is divergent light and is converted into approximately collimated light by the condensing lenses 142 and 143. However, in order to obtain sufficient collimated light, a convex lens is used. It is necessary to line up about two sheets, and the size is increased. Therefore, as shown in FIG. 7B, by making the emission surface of the light integrator 151 convex, one collimating lens and the light integrator are integrated to suppress the degree of divergence of the emitted light. It is possible to reduce the size of the device by using a single sheet.

FIG. 7C is a configuration diagram showing a modification of the optical splitter 132W in FIG. In FIG. 6, the light branching portion 132W uses the incident reflecting surface 158 to input light into the device. Therefore, it is preferable from the viewpoint of light utilization efficiency that the input beam diameter and the size of the incident reflecting surface are the same size. Therefore, there is a problem that it is difficult to secure a sufficient reflecting surface size. Therefore, the light branching portion 132W in FIG. 7C does not use the incident reflecting surface 158, and the illumination light emitted from the condenser lens 143 passes through the main surface 156 of the light branching portion 132W via the optical path correction prism 163. It is configured to be input. The illumination light input into the light branching portion 132W is reflected by the other main surface 155 and confined within the light branching portion 132W. Since the main surface 155 has a sufficient size, there is an advantage that the optical branching portion 132W can be thinned while reducing the loss at the time of coupling to the optical branching portion 132W.

So far, the configuration using the output reflecting surface group for the light branching section 132W has been described, but the function of the output reflecting surface group 157 may be realized by a different method. For example, a polarizing diffraction grating or a polarizing volume hologram may be used. A diffraction grating or a volume hologram is formed, and part of the illumination light propagated through the element is deflected to the image display section 121 for illumination.

FIG. 7D is a configuration diagram showing a modification of the video generation unit 101. As shown in FIG. When a monochromatic light source is used in the light source unit, or when the LEDs and laser light emitting units of each color such as red, green and blue mounted in the light source unit are small and arranged very close to each other, the optical integrator in FIG. 6 is not used. Both colors can be mixed in total reflection in the light branching portion 132W. Therefore, as shown in FIG. 7D, the light emitted from the light source 150 can be configured to be substantially collimated by the condensing lenses 142 and 143 and enter the light branching portion 132W, thereby miniaturizing the device.

In the configuration shown in FIG. 7D, due to the relationship between the light source 150, the condenser lenses 142 and 143, and the projection section 122, a conjugate image of the light source 150 is generated at the exit pupil position 122p of the projection section 122, which has a substantially conjugate positional relationship. Therefore, when the user sees the image through the light guide plate, it appears that the conjugate image of the light source 150 is superimposed in front of the image, and the visibility of the image deteriorates.

Further, as mentioned above, the light guide plate has the function of duplicating the exit pupil of the projection section 122 to enlarge the eyebox. Therefore, especially when a beam splitter mirror array type light guide plate is used, the conjugate image is duplicated on the light guide plate and the visibility of the image is greatly reduced.

Therefore, the diffuser plate 161 is provided between the condensing lenses 142 and 143 and the light branching portion 132W as a brightness uniforming means as in the above. Light is diffused by the diffusing plate, and the outline of the conjugate image of the exit surface 153 of the light integrator 151 is blurred, thereby reducing the visibility and improving the image quality. On the other hand, since the diffusion plate 161 does not affect the projection side, the resolution of the output image is not deteriorated. Further, as described above, the polarizing filter 162 may be arranged between the light branching section 132W and the diffusion plate 161. FIG.

As described above, with the configuration shown in this embodiment, it is possible to provide an image projection apparatus having an illumination optical unit that achieves both compactness of the optical system and high image quality, and an image display unit that uses the illumination optical unit to display an image.

FIG. 8 is a schematic diagram of the configuration of the image generation unit 101 when a transmissive liquid crystal panel is used for the image display unit 121 in this embodiment. The light from the light source 150 in the image generation unit 101 is color-mixed and homogenized by the light integrator 151 , and then converted into substantially collimated light by the condensing lenses 142 and 143 . When a transmissive liquid crystal panel is used for the image display section 121, it is not necessary to mount a light branching section, and the image display section 121 is illuminated with light substantially collimated by the condensing lenses 142 and 143. FIG. The light transmitted through the image display unit 121 is converted in the polarization direction only in pixels that are turned ON, is transmitted through the polarizing filter 160 mounted in accordance with the image display unit 121, and is projected as an image through the projection unit 122. FIG.

In the configuration of the image generation unit 101 of this embodiment as well, due to the relationship between the condensing lenses 142 and 143 and the projection unit 122, the conjugate image of the output surface 153 of the light integrator 151 is in a substantially conjugate positional relationship. It occurs at the exit pupil position 122p. Therefore, when this optical system is applied to an HMD, the user sees the conjugate image of the exit surface 153 of the light integrator 151 superimposed in front of the virtual image of the image display unit 121, resulting in poor visibility of the image. decreases. Furthermore, as described above, in the case of an HMD using a light guide plate, the light guide plate has a function of duplicating the exit pupil of the projection unit 122 in order to enlarge the eyebox. Therefore, especially when a beam splitter mirror array type light guide plate is used, the conjugate image is duplicated on the light guide plate, further reducing the visibility of the image.

Therefore, a diffuser plate 161 is arranged as luminance equalization means for reducing visibility by blurring only the conjugate image without affecting the resolution of the image. By arranging the diffusion plate 161 as far away from the exit surface 153 of the light integrator 151 as possible, a diffusion plate with a small diffusion angle can obtain the effect of reducing the visibility of the conjugate image and improve image quality. There is an advantage that deterioration of utilization efficiency can be suppressed. Therefore, by arranging the diffusion plate 161 between the condenser lens 143 and the image display section 121, it is possible to improve both the light utilization efficiency and the visibility.

Also, in order to improve the contrast, a polarizing filter 162 that transmits only light in a predetermined polarization direction may be placed on the illumination side. By doing so, the effect of improving the contrast can be obtained.

Similarly, the contrast of the image projected by the projection unit 122 can be improved by arranging the polarizing filter 160 that transmits only a predetermined polarization direction between the image display unit 121 and the projection unit 122 .

FIG. 9 is a schematic configuration diagram of the image generation unit 101 when a digital micromirror device (DMD) panel is used for the image display unit 121. As shown in FIG. Light emitted from the light source 150 in the image generator 101 is mixed and homogenized by the light integrator 151 . In a DMD panel that expresses ON/OFF of a pixel by changing the reflection angle of light depending on the angle of the mirror, illumination light needs to be obliquely incident on the panel. At this time, the illumination optical system also requires a prism for correcting aberration due to oblique incidence. Therefore, a lens system for collimating the light from the light integrator 151 and an aberration correction prism are required, resulting in an increase in size. Therefore, in FIG. 9, the condensing lens 142 and the condensing lens in the latter stage are formed as a concave compound prism 170 in which the aberration correcting prism is integrated. The illumination light, which is collimated by the condenser lens 142 and the concave compound prism 170 and whose aberration due to oblique incidence is corrected, passes through the light branching section 132 and illuminates the image display section 121 .

In a DMD panel that expresses ON/OFF of a pixel by changing the reflection angle of light depending on the angle of the mirror, the light beam angle of the ON light is converted to an angle at which it is totally reflected by the reflecting surface 171 of the light branching unit 132, and the light is reflected from the DMD panel. output. The image light totally internally reflected by the reflecting surface 171 of the light branching section 132 is projected as an image through the projection section 122 .

Even in the configuration of the image generation section 101 using the DMD panel, the conjugate image of the exit surface 153 of the light integrator 151 is in a substantially conjugate positional relationship due to the relationship between the condenser lens 142, the concave compound prism 170, and the projection section 122. It occurs at the exit pupil position 122p of a certain projection unit 122. FIG. Therefore, when this optical system is applied to an HMD, the user sees the conjugate image of the exit surface 153 of the light integrator 151 superimposed in front of the virtual image of the image display unit 121, resulting in poor visibility of the image. decreases. Furthermore, as described above, in the case of an HMD using a light guide plate, the light guide plate has a function of duplicating the exit pupil of the projection unit 122 in order to enlarge the eyebox. Therefore, especially when a beam splitter mirror array type light guide plate is used, the conjugate image is duplicated on the light guide plate, further reducing the visibility of the image.

Therefore, in order to blur only the conjugate image and lower the visibility without affecting the resolution of the image, a diffuser plate 161 is arranged as luminance uniforming means. By arranging the diffuser plate 161 as far away from the exit surface 153 of the light integrator 151 as possible, the effect of reducing the visibility of the conjugate image can be obtained with a diffuser plate having a small diffusion angle, and the image quality can be improved. There is an advantage that deterioration of light utilization efficiency can be suppressed. Therefore, by arranging the diffusion plate 161 between the concave compound prism 170 and the light branching portion 132, it is possible to improve both the light utilization efficiency and the visibility.

As described above, in the compact illumination optical system using the light integrator, the structure shown in this embodiment can provide an HMD that achieves both light utilization efficiency and visibility.

In this embodiment, an application example of the HMD equipped with the video generation unit 101 described in the first and second embodiments will be described. FIG. 10 is a diagram showing a usage example of the HMD in this embodiment. In FIG. 10, the same components as those in FIG. 4A are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 10 , content is displayed in a video (virtual image) display area 111 from the HMD 10 in the field of view of the user 2 . For example, a work procedure manual 301 and a drawing 302 for inspection and assembly of industrial equipment are displayed. Since the image display area 111 is limited, if the work procedure manual 301 and the drawing 302 are displayed at the same time, the content becomes small and visibility deteriorates. Therefore, visibility is improved by performing head tracking in which the direction of the head of the user 2 is detected by an acceleration sensor and changing the display content according to the direction of the head. That is, in FIG. 10, the work procedure manual 301 is displayed in the video display area 111 when the user 2 faces left, but when the user turns right, the drawing 302 is displayed in the video display area 111, as if , the work procedure manual 301 and the drawing 302 can be displayed as if there is a virtual image display area 112 that allows visual recognition in a wide field of view.

As a result, the visibility is improved, and the user 2 can perform the work while visually recognizing the work target (equipment, tools, etc.) and the work instructions at the same time. can be reduced.

FIG. 11 is a functional block configuration diagram of the HMD in this embodiment. In FIG. 11, the same components as in FIG. 1 are denoted by the same reference numerals, and descriptions thereof are omitted. 11 differs from FIG. 1 in that a head tracking function is added. That is, the image signal processing section 103A of the HMD 10 is provided with a head tracking section 103H. The head tracking unit 103H detects the direction of the head of the user 2 based on information from the acceleration sensor 106H of the sensing unit 106A, and changes display content according to the direction of the head.

HMDs are used indoors and outdoors. Therefore, it is necessary to adjust the brightness of the displayed image according to the brightness of the surrounding environment. As an example, an illuminance sensor 106M may be mounted in the sensing unit 106A, and the brightness of the image displayed by the image signal processing unit 103A may be adjusted according to the output of the illuminance sensor 106M.

Although the embodiments have been described above, the present invention can reduce the amount of materials used by miniaturizing the optical system while improving the quality of the displayed image of the image projection device. Therefore, it is possible to reduce carbon emissions, prevent global warming, and contribute especially to item 7 energy for realizing SDGs (Sustainable Development Goals).

Moreover, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the functional configurations of the HMD and the video generation unit 101 described above are classified according to main processing contents for easy understanding. The present invention is not limited by the method of classifying the constituent elements or their names. The configuration of the HMD and image generation unit 101 can be classified into more components according to the processing content. Also, one component can be grouped to perform more processing.

It goes without saying that the present invention can be applied not only to HMDs but also to other video (virtual image) display devices having the configuration of the video generation unit 101 described in each embodiment.

Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

1: video projection device, 10: HMD, 101: video generation unit, 102: control unit, 103: image signal processing unit, 104: power supply unit, 105: storage unit, 106: sensing unit, 107: communication unit, 108 : audio processing unit, 109: imaging unit, 91 to 93: input/output unit, 111: image display area, 112: virtual image display area, 120: illumination optical unit, 121: image display unit, 122: projection unit, 123 : light guide section 132W: light branching section 150: light source 151: light integrator 152: entrance surface 153: exit surface 154: scattering particles 155, 156: principal surfaces 157: exit/reflection surface group 158: incident reflecting surface, 160, 162: polarizing filter, 161: diffusion plate, 170: concave compound prism

Claims (15)

An illumination optical unit that illuminates an image display unit that displays an image,
a light source that emits light;
a lens unit that converts divergent light from the light source into substantially collimated light;
an optical path of illumination light directed to the image display unit on which light emitted from the lens unit is incident;
The illumination optical unit, wherein the light branching unit has two or more output reflection surfaces for outputting the illumination light. The illumination optical unit according to claim 1,
the light branching portion has a pair of substantially parallel main surfaces that confine illumination light by internal reflection;
The illumination optical unit, wherein the distance between the two or more output reflection surfaces is smaller than a predetermined length of one side of the image display unit. The illumination optical unit according to claim 1,
the light branching portion has a pair of substantially parallel main surfaces that confine illumination light by internal reflection;
the reflective film formed on the output reflective surface is a polarizing reflective film,
An illumination optical unit, wherein a polarizing filter is arranged between the light branching unit and the projection unit. The illumination optical unit according to claim 1,
the output reflecting surface is a partially reflecting surface that partially reflects light;
The illumination optical unit, wherein the reflectance of the two or more output reflecting surfaces increases as the distance from the incident portion of the light branching unit increases. The illumination optical unit according to claim 1,
The illumination optical unit, wherein the light branching unit and the image display unit are arranged with an interval of 1 mm or more. The illumination optical unit according to claim 1,
An illumination optical section, wherein the arrangement direction of the two or more output reflection surfaces of the light branching section and the short side direction of the effective area of the image display section are substantially parallel to each other. The illumination optical unit according to claim 1,
a light integrator into which light from the light source is incident and emitted to the lens unit;
The light integrator has a shape similar to a rectangular prism or a cylinder, and is filled with a predetermined highly transparent medium A, and is filled with scattering particles from a highly transparent medium B having a refractive index different from that of the medium A. and an illumination optical unit. The illumination optical unit according to claim 1,
a light integrator into which light from the light source is incident and emitted to the lens unit;
The light integrator has a shape similar to a square prism or a cylinder, and the inside thereof is a layer filled with a medium A having a predetermined high transparency, and scattering particles from a medium B having a high transparency and a refractive index different from that of the medium A. is separated into a layer filled with . The illumination optical unit according to claim 1,
An illumination optical unit, comprising a luminance equalizing unit between the light branching unit and the lens unit. The illumination optical unit according to claim 1,
a light integrator into which light from the light source is incident and emitted to the lens unit;
The light integrator has a shape similar to a square prism or a cylinder, and the inside is filled with a medium A having a predetermined high transparency,
An illumination optical section, comprising a diffuser plate as luminance equalizing means between the light branching section and the lens section. A video projection device that projects a video,
a video display unit for displaying video;
an illumination optical unit that illuminates the image display unit;
A projection unit that magnifies the image light of the image display unit and projects it as a virtual image,
The illumination optical unit is
a light source that emits light;
a light integrator in which the light from the light source is incident and the interior of which is filled with a predetermined highly transparent medium and scattering particles;
having a lens unit that converts the light from the light integrator into substantially collimated light;
An image projection apparatus, comprising luminance equalizing means between the image display section and the lens section. The video projection device according to claim 11,
The image projection device, wherein the image display section is composed of a transmissive liquid crystal panel. The video projection device according to claim 11,
an optical path of illumination light directed to the image display unit on which light emitted from the lens unit is incident, and a light branching unit for branching the light from the image display unit to the optical path on the projection unit side,
the light branching unit has a pair of substantially parallel principal surfaces for confining the illumination light by internal reflection, and two or more emission reflection surfaces for emitting the illumination light,
An image projection apparatus, wherein a polarizing filter is arranged between the light branching section and the projection section. The video projection device according to claim 11,
A light guide unit that duplicates the image light from the projection unit and transmits it to a user's pupil,
The image projection device, wherein the light guide section has two or more exit reflection surfaces that are partial reflection surfaces, and functions as a head-mounted display that displays an image within a user's visual field. The video projection device according to claim 11,
a power supply unit that supplies power;
a sensing unit that detects the position and orientation of the user;
an audio processing unit that inputs or outputs an audio signal;
A video projection apparatus, comprising: a control section that controls the power supply section, the sensing section, and the audio processing section.

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